1. Field of the Invention
This invention relates to the field of network emulation and, more particularly, to emulation of wireless networks.
2. Description of the Related Art
Mobile computing networks provide environments and scenarios that challenge current computing paradigms. Current network protocols frequently are unable to efficiently deal with mobility issues regarding both nomadic data and devices. In consequence, various software-based tools, referred to as simulators, and hardware-based tools, referred to as emulators, have been developed by the research community to study and improve the performance of network protocols, determine data restriction points in networks, and reduce the cost of hardware implementation.
While software-based simulation tools do provide researchers with the ability to model various networking scenarios, such systems have disadvantages. One disadvantage is that the duplication of the software development process for purposes of simulation, for example to support new operating system platforms and/or newly introduced wireless technologies, is costly, time consuming, and oftentimes impractical. As an example, to support a new network technology, each component used by a software-based network simulator, from traffic generators, Transmission Control Protocol (TCP) implementation, to application level interfaces, would have to be developed and implemented as an object file within the simulator library. Further development efforts would be required to use these objects or software components across different computing platforms.
Another disadvantage is the amount of time simulators require for performing different simulations. Typically, simulators required an amount of time that is several orders of magnitude larger than the amount of time that is being simulated. For example, on average, several hours of simulation time are needed to simulate several minutes of a given real-time network scenario. As software simulators already require a significant amount of time to model wired and/or wireless networks, the introduction of rapid mobility conditions and complex propagation models relating to mobile networks further challenges the utility and suitability of software-based simulators. Unfortunately, efforts to improve software-based simulator performance by simplifying modeling tasks through the reduction of the number of modeling parameters used during a simulation can lead to misleading, if not erroneous results.
Wire-line emulators provide researchers with a faster and more efficient alternative than software-based simulators. Several different wire-line emulators have been developed to replicate the conditions of end-to-end network delays. For example, the End-to-End Emulator as described in C. Bolot, End-to-End Packet Delay and Loss Behavior in the Internet, ACM Computer Communication Review, Vol., 23, No. 4, pp. 289–298 (October 1993), seeks to imitate the Internet by providing end-to-end network delay using Internet Control Message Protocol (ICMP) packets as a real time traffic source. The Ohio Network Emulator (ONE) as described in M. Allman, A. Caldwell, S. Ostermann, ONE: The Ohio Network Emulator, TR-19972, School of Electrical Engineering and Computer Science, Ohio University (August 1997), is able to emulate transmission, queuing, and propagation delay between two computers interconnected by a router.
Presently, however, wire-line emulators do not account for characteristics of rapid mobility networks or complex signal propagation models. As such, conventional wire-line emulators are not available or are unable to model mobile networks.